Alpinestars does not express any length of time for there products to be warranted, Here is an excerpt from there site:
We guarantee our merchandise to be free of manufacturing defects. If an item you have received is defective, we will be glad to assist you with processing a refund. For help with processing your return, please contact our Customer Service team â€“ (US) 1-800-409-0903 / (INT) 1-310-891-0222 or contact us here: http://www.alpinestars.com/contact